Socket assembly having ground pin

ABSTRACT

This invention is directed at an electric socket having an insulating insert engaged within a metal shell. The insert has a ground pin associated with it comprising a head portion and a shank portion extending therefrom. The head portion is adapted to fit within a slot formed in a flange of the insert so that the upper surface of the head portion lies on the same plane as the upper surface of the flange and the shell is electrically engaged with the head portion.

United States Patent Inventor Richard J. Mangini Hudson, Mass.

App]. No. 763,208

Filed Sept. 27, 1968 Patented June 1, 1971 Assignee United-Carrincorporated Boston, Mass.

SOCKET ASSEMBLY HAVING GROUND PIN 1 Claim, 6 Drawing Figs.

u.s.cl 339/14,

339/170 lnt.Cl non 3/06 Field 6: Search 339/14,

[56] References Cited UNITED STATES PATENTS 1,782,527 11/1930 Bennett339/14 2,959,761 11/1960 Weber et al.. 339/170 Primary Examiner-MarvinA. Champion Assistant Examiner-Robert A. Hafer Att0rneysPhilip E.Parker, Gordon Needleman, James R.

OConnor, John Todd and Hall and l-loughton ABSTRACT: This invention isdirected at an electric socket having an insulating insert engagedwithin a metal shell. The insert has a ground pin associated with itcomprising a head portion and a shank portion extending therefrom. Thehead portion is adapted to fit within a slot formed in a flange of theinsert so that the upper surface of the head portion lies on the sameplane as the upper surface of the flange and the shell is electricallyengaged with the head portion.

' ,PATEN'TEDJUN nan (PRIOR ART) F l G.

FIG. 3

F l G. 5

F IG. 6

iNvENToR RICHARD J. MANGlNl W Mala ATTORNEY SOCKET ASSEMBLY HAVINGGROUND PIN BACKGROUND OF THE INVENTION There are a number ofapplications where an electric bulb socket is required to be groundedthrough its shell and through a ground pin which is engaged therewith.Some of the early socket designs, many of which are still in use,utilized a plug button or other attaching device as a means of groundingthe shell to a support, such as the chassis of a car. The socket shownin FIG. I uses an insulating insert 1 within which a pair ofspring-loaded terminals 2 are axially located. A ground pin 3, oftubular configuration, is slid into an axial engagement aperture formedin the upper surface of the insert I and through a flange 4 whichextends from a wall of the insert. A lip formed on the upper surface ofthe ground pin 3 abuts the upper surface of the insert I for about 270of the circumference of the ground pin 3. The remaining portion of thecircumference is sheared downwardly to overlie the flange 4 with thesheared portion of the lip extending slightly beyond the flange 4. Thesubassembly of the insert 1 and the ground pin 3 can now be dropped intoa metal socket shell 5 which has a shoulder element formed therein. Thepin 3 and a portion of the insert 1 can pass beyond the area defined bythe socket 5 while the lower surface of the flange 4 butts against theshoulder. The socket shell 5 is then bumped inwardly to abut the shearedportion of the lip to form an electrical and mechanical engagement.

There are several disadvantages to this method for forming a ground. Forinstance, the cost of the secondary operation is rather high in relationto the part being manufactured. Furthermore, the position of the shearedpiece must be accurately predetermined to assure satisfactory engagementbetween the indentation formed in the socket shell and the ground pin.This last requirement is made even more difficult because the shearedpiece comes to rest on top of the flange of the insert. Note that whenthe shell is bumped inwardly it pushes against the sheared portion ofthe lip creating the danger of breaking the sheared portion therebydestroying the required electrical connection.

SUMMARY OF THE INVENTION This invention is directed at a lamp socketwhich comprises a tubular metal shell and an electrically insulatinginsert. The insert assembly includes a plastic body having means ofengaging a pair of terminal elements as well as means of engaging a pairof contacts adapted to engage a light bulb. The insert is also engagedto a headed ground pin which fits within a slot formed in a flange ofthe body. The head of the ground pin has its upper surface on the sameplane as the upper surface of the flange and also has an arced wallforming a continuation of the outer wall of the flange.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a top plan view ofa socketwhich forms part of the prior art;

FIG. 2 is a side elevation of the insert subassembly of the inventionshowing spring-loaded contacts, blade terminals and the ground pin onthe opposite side;

FIG. 3 is a top plan view of the insert subassembly shown in FIG. 2;

FIG. 4 is a side elevation of the insert subassembly shown in FIG. 2with the ground pin uppermost;

FIG. 5 is a side elevation of the ground pin; and,

FIG. 6 is a side elevation of the insert subassembly engaged to a socketshell, the socket shell broken off.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing there is shown asocket 10 comprising a metallic shell 12, an insulating insert 14 flxedwithin the metallic shell 12 and having a pair of blade terminations I6and a ground pin 18 engaged therewith.

The insert 14 is formed of an organic polymeric material such as ageneral purpose phenolic, modified polyphenyleneoxide, a polyacetalresin or nylon. It has a pair of sidewalls 20, 22 in spaced parallelrelationship with each other connected by a pair of spaced arced endwalls 24. The insert 14 includes two apertures 26, 28 which are axiallyformed through its upper surface 30 and which extend down through thelower surface 32. Retaining slots (not shown) extend on each side of theapertures 26, 28 respectively. These slots are formed on the lowersurface 32 but not on the upper surface 30. An arced flange 38 extendsfrom the sidewall 22 and another arced flange 40 extends from thesidewall 20 on the same plane as the flange 38. An engagement aperture42 is formed through the arced flange 40 having an axis in spacedparallel relationship to the axes of the apertures 26, 28 and beingenclosed for the major portion of its length by an arced coveringportion 44. The engagement aperture 42 divides the flange 40 into twoportions as shown in FIG. 3. The covering portion 44 can act as anindexing means when engaged with a notch formed through the shoulder ofthe shell 12. The engagement aperture 42 is adapted to receive theground pin 18 which comprises a solid cylindrical shank portion 46 andan integral head portion 48. The head portion 48 has a pair of flatsidewalls 50, 52 in angular relation to each other merging into an arcedrear surface of the head portion 48 which is a continuation of the shankportion 46. The head portion 48 fonns a shoulder 54 with the shankportion 46.

To engage the ground pin 18 with the insert 14 the shank portion 46 ispassed down through the engagement aperture 42 until the shoulder 54butts against the upper edge of the covering portion 44. In thisposition the upper surface of the head portion 48 is flush with theupper surface of the arced flange 40 and the rounded edge of the headportion 48 provides a continuation of the arced surface of the flange40. Each portion of the flange 40 adjacent the head portion 48 isehamfered.

A pair of tubular contacts 56 each a headed eyelet comprising a bodyportion having one end closed by a flangelike portion. The body portionof the contact 56 is circumscribed by a compression spring 58 which isbutted against the flangelike portion and then a single subassembly ofthe contact 56 and the spring 58 is placed into each aperture 26, 28 sothat the lower terminal end of the compression spring 58 butts againstthe upper surface of the insert 14 and then the open end of the contact56 is flared outwardly to engage an internal shoulder formed in closeproximity to the upper surface of the insert 14 and in the wall of eachof the apertures 26, 28. The contact 56 is now adapted to move in anaxial direction up and down against the compression spring 58 butthrough the flaring operation is securely held in engagement with theinsert 14.

The terminals 16 each comprises a comparatively broad rectangular bladeportion having an integral engagement portion extending from a shortedge thereof. The engagement portion comprises a flexible strip ofnarrower width than the blade portion which is bent back upon itselfdefining a pair of arms. One of the arms is shorter than the other andboth arms are bowed outwardly. To engage a terminal 16 with a tubularcontact 56, the engagement portion is passed into one of the apertures26, 28 from the lower surface 32 until the arms of the engagementportion pass into the contact 56 while the blade portion engages in theslots. A wiping contact is thereby maintained between the engagementportion and the inner surface of the contact 56.

The tubular shell 12 and the insert subassembly are engaged in thefollowing manner: The tubular shell 12 has two inturned shouldersadjacent one end, one of the shoulders having a notch formedtherethrough. The insert subassembly is dropped down into the shell withthe contacts 56 pointing away from the inturned shoulders and theflanges 38, 40 are butted against the shoulders while the coveringportion 44 rests within the notch formed in one of the inturnedshoulders. The metal of the shell is now bumped inwardly providing adimple or protuberance as shown in FIG. 6 whereby it overlies shell, theprotuberance overlying a portion of the head portion in abuttingrelation, and the insert having means associated therewith forelectrically engaging a bulb or the like and the head portion having anupper surface and the insert having an external flange having an uppersurface, both of said upper surfaces being on the same plane when theground pin is fully engaged with the insert.

1. An electric socket comprising a shell providing a cavity, an insertengaged within the cavity having a slot formed therein, and a ground pinhaving a head portion and a shank portion, the head portion set withinthe slot and engaging with an inwardly projecting protuberance formed inthe tubular shell, the protuberance overlying a portion of the headportion in abutting relation, and the insert having means associatedtherewith for electrically engaging a bulb or the like and the headportion having an upper surface and the insert having an external flangehaving an upper surface, both of said upper surfaces being on the sameplane when the ground pin is fully engaged with the insert.